This invention relates to an agricultural harvesting machine for baling hay or the like, and more particularly to a control mechanism for actuating a bale tying mechanism and controling the length of the bale.
An agricultural baler conventionally includes a mechanism for tying a bale with either twine or wire after the bale has reached a predetermined length, after which the bale is discharged from the baler. The tying mechanism is conventionally driven at appropriate intervals through aa single revolution clutch, that is engaged by actuation of a tripping device responsive to the length of the bale. Most current balers utilize similar tripping devices that measure the length of the bale and actuate the clutch when the bale reaches the predetermined size, the original tripping mechanism of this type being developed in Germany and being widely used because of its simplicity. U.S. Pat. No. 2,988,115 shows a bale tying mechanism and tripping device of the above general type, and U.S. Pat. No. 3,371,596 also discloses a tripping mechanism of the above type.
Generally said tripping devices utilize a vertically swingable trip arm that is swung upwardly by engagement with a wheel that is driven by a bale measuring wheel that rotates as the bale increases in length. When the arm reaches its tripping position, it permits the actuation of a clutch, that in turn actuates the tying mechanism. After the clutch is actuated, means are provided for moving the wheel out of engagement with the arm, which permits the trip arm to fall until a stop on the trip arm engages the wheel, following which the wheel again engages the arm to raise the arm and repeat the cycle for another bale. Conventionally the stop on the arm is adjustable to vary the distance that the trip arm has to be swung before it again actuates the clutch and to consequently vary the length of the bale.
One problem with the above devices resides in the fact that as the trip arm falls against the stop, the natural resilience of the parts causes the arm to bounce, and if the wheel again engages the arm while the arm has bounced off the wheel, the next bale will be shorter in length since the arm will not have to travel so far before it again reaches the trip position. Also, the fields in which the balers are operated are generally relatively rough, and the roughness is compounded by the increasing speed at which the balers are operated, so that the entire machine is frequently bouncing, which causes the trip arm to bounce on the stop when it is free of the wheel. Thus, if the baler strikes a substantial hole or a bump while the trip arm is free of the wheel, it is possible that the wheel will engage the arm a substantial distance away from the stop, again causing the next bale to be substantially shorter. The resulting irregular bale lengths has presented more of a problem recently with the increasing use of automatic bale handling machines, which require a relatively uniform bale size.